A solar panel sits in front of the stage where Rep. Rick Nolan, D-Minn., (right) speaks to the audience and other special guests Sen. Al Franken, D-Minn., (left), Alan Hodnik, CEO of Minnesota Power and the adjutant general of the Minnesota National Guard Maj. Gen. Richard Nash during a ceremony to sign an agreement to build a 10 megawatt solar energy array covering 100 acres at Camp Ripley.3 / 3

DULUTH - Tucked away on the sprawling, 53,000-acre Camp Ripley military installation near Brainerd, protected from exploding artillery shells and rumbling tanks, an open field soon will be covered with enough solar panels to power 2,000 homes.

Minnesota Power and the Minnesota National Guard are expected to sign a partnership today to build a $25 million solar farm that will supply Camp Ripley with much of its electrical needs.

The 10 megawatt — equal to 10 million watts — solar farm will cover 100 acres and will be the largest contiguous solar farm in Minnesota.

It also will be the largest solar farm on any National Guard base in the nation, and will help the Guard meet its orders from the Department of Defense to use more renewable energy and become more energy efficient. The project also includes the installation of a smart grid system at the base along with backup generators that will allow the facility to operate even if the public electrical grid shuts down.

The Guard hopes to cut Camp Ripley’s energy bill by 30 percent.

The sprawling solar farm also will help Duluth-based Minnesota Power meet its state-mandated requirement to generate 1.5 percent of its electricity from solar sources by 2020.

Under the 2013 law, regulated, shareholder-owned utilities like Minnesota Power and Xcel Energy must add solar to their mix of energy sources. Minnesota Power will need to add about 33 megawatts to satisfy the state law. Currently, all of the solar electric systems in the Minnesota Power region combined amount to only 0.5 megawatt, said Al Rudeck, Minnesota Power vice president of strategy and planning.

The Camp Ripley Project, which is scheduled to be on line by 2016, will meet nearly one-third of Minnesota Power’s state-mandate requirement, Rudeck said.

Running at peak capacity, on sunny summer days, the solar farm will produce more energy than Camp Ripley uses, with the excess energy moving out on the grid and giving the Guard a break on its power costs.

“The Minnesota National Guard and specifically Camp Ripley has been long looking for ways to increase our environmental stewardship. This (agreement) marks a milestone along our path to making that vision a reality,” Maj. Gen. Rick Nash, Minnesota National Guard adjutant general, said in a statement announcing the project. “The Minnesota National Guard is committed to working with local partners in the government and the private sector, like Minnesota Power, to assist us in our pursuit of sustainable infrastructure.”

The project is one of dozens planned across Minnesota where the state legislation, falling prices for solar panels and a 30 percent federal tax credit are combining to spur a solar boom.

So far the state’s largest operating solar farm is near Slayton, a 2 megawatt array that includes 7,040 solar panels that cover more than seven football fields on what had been a cornfield. That’s enough electricity to power 250 homes. It’s owned by Ecos Energy, which sells the power to Minneapolis-based Xcel Energy.

Another huge array sits atop the Minneapolis Convention Center. The 600 kilowatt system is made up of 2,613 panels and has been churning out electricity since 2010. St. John’s University has a 400 kilowatt system.

In Grand Rapids, the Minnesota Department of Natural Resources earlier this year installed a 105 kilowatt system at its regional headquarters. St. Louis County has a 30,000 watt solar farm on the roof of its Government Services Center — the largest in Duluth — and a test site to measure which panels work best in the Northland environment. Even larger solar projects are in the works.

More and more people are bolting solar panels onto their home or garage roofs. Experts say a home rooftop 5 kilowatt system will pay for itself in about 10 years. With incentives, a $25,000 system can be installed for about $8,000 and generate a profit of more than $24,000 over 25 years, roughly the lifespan of most solar panels.

Minnesota Power expects to meet its state mandate by adding about 4 megawatts of small-scale, household or small-business size solar systems across the region. The rest, about 19 megawatts beyond the Camp Ripley project, will likely be other large-scale solar farms.

“We’re talking to other customers where we think it can be mutually beneficial to meeting their goals and ours,’’ Rudeck said.

Minnesota Power is looking mostly at brownfield sites, land that’s not being used for other projects, farming or forestry. Ground sites are far less expensive than rooftop sites, Rudeck noted, and are easier to hook up and service.

The 2013 state legislation bill also allows private citizens or corporations to build solar arrays up to 1 megawatt and requires utilities to hook them up to their grid. The previous limit was just 40 kilowatts.

Still, solar power isn’t likely to meet a majority of Minnesota’s electrical needs anytime soon. At best, solar panels are generating at peak capacity about 17 percent of the time in northern Minnesota — they don’t work at night or on very cloudy days. And even on sunny days in winter, when the sun is at a low angle, they don’t generate at full capacity for very many hours, Rudeck said.

That won’t work to power the major customers in Minnesota Power’s service area, namely taconite plants and paper mills that gobble energy 24 hours a day, seven days a week, 365 days a year. Minnesota Power, in fact, has the highest sustained demand of any utility in the nation.

“Most utilities see their demand fall considerably in the evening when people go home from work. But our line is nearly flat,’’ Rudeck said. “Solar will clearly be part of our renewable mix. But, like wind, solar can’t be the complete answer.”

Minnesota Power has set a goal of having about one-third of its generation from renewables — solar, wind and hydro — by 2025, with about one-third natural gas and one-third for coal-fired power plants.

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